U.S. Vice President Biden waves as he walks out of Air Force Two at the airport Dec. 4 in Beijing. / Getty Images

by Calum MacLeod, USA TODAY

by Calum MacLeod, USA TODAY

BEIJING - A few hours after having laughed it up with workers in Tokyo, U.S. Vice President Joe Biden found himself in face-to-face meetings Wednesday with Chinese President Xi Jinping over China's controversial new air defense zone.

The China leg of Biden's swing through Asia was supposed to be on how the two nations could cooperation on economic matters but China's recent announcement that it controls the air space over the East China Sea, including island territories of Japan, made for a tense mood.

Biden was greeted with state-controlled press stories lashing out at the United States for standing with Japan to complain about the air defense zone that China says requires all aircraft passing through to notify it of their presence.

The announcement is the latest attempt by China's Communist government to lay claim to nearly 1 million square miles of sea and all the energy and fishing resources it contains.

After five hours of meetings, a noticeably somber Biden told the assembled press that the U.S.-China relationship will significantly affect the course of the 21st century, and, done right, the possibilities are limitless.

"Candor generates trust," Biden said of Xi's "candid" attitude. "Trust is the basis on which real change - constructive change - is made."

What was said was not discussed. But though the United States sent military aircraft into the zone, the Obama administration said it had asked U.S. airliners to abide by China's demand.

Japan Prime Minister Shinzo Abe had hoped the United States would not kowtow to China on the matter, according to the Japan news media, and demand that China reverse itself on the air zone. But Biden did not say if he asked China to do so, or if the United States would ignore it.

In Washington, Defense Secretary Chuck Hagel called China's announcement of the zone "destabilizing" and complained that it had come "so unilaterally and so immediately without any consultation." But he too did not say that the USA would defy China.

In his public remarks after the Biden meeting, Xi extolled the benefits of closer U.S.-China ties as he laid out "profound and complex changes" underway in Asia and across the globe.

"The world, as a whole, is not tranquil," Xi said.

The air defense zone covers some areas of ocean that are far closer to Japan, Taiwan and South Korea, and includes waters considered international by the United States. The zone also covers the Senkaku Islands, annexed by Japan decades ago but that China says belong to it.

Many nations including the United States have set up air defense zones that extend from their shorelines to protect against enemy aircraft. But China's zone is extraordinary in its outward extension, and unlike the United States China requires aircraft that are passing through the zone but not landing in its country to notify Chinese authorities of their presence.

The issue came up at length at the beginning and again near the end of the meeting with Xi, senior Obama administration officials said to the Associated Press.

The day before, Biden spent a the day in Japan where he and Abe had dinner and Biden visited Shibuya, a bustling Tokyo district and fashion center where he toured a technology company and joked with young employees in a chic lunchroom overlooking Tokyo's sprawling skyline.

In Beijing, Biden arrived on a day when the state-run China Daily charged in an editorial that Washington with "turning a blind eye to Tokyo's provocations," and warned that Biden would hit a dead end should he come "simply to repeat his government's previous erroneous and one-sided remarks."

In a visit with Chinese youngsters waiting to get visitor visas at the U.S. Embassy, Biden criticized his authoritarian hosts by telling the children that in American children are rewarded rather than punished for challenging the status quo.

"I hope you learn that innovation can only occur where you can breathe free, challenge the government, challenge religious leaders," Biden said, though in China the ruling Communist part is officially atheist.

Wang Dong, head of the Center for Northeast Asian Strategic Studies at Peking University, said the goal of the zone is to get Japan to agree that there should be negotations over the Senkaku Islands, which China calls the Diaoyu islands.

"One of China's main goals is to put more pressure on Japan and urge Japan to recognize the dispute over the Diaoyu Islands, and reciprocate the Chinese leaders' proposal to seek a diplomatic solution," he said.

Chinese and Japanese ships and planes have come into increasingly perilous proximity near the islands over the past year. China wants the USA to join it in pressuring Japan.

Sun Zhe, director of the Center for Sino-U.S. Relations at Qinghua University in Beijing, said the U.S. should reduce "provocative" actions such as flying B-52s through the zone, or risk turning China's dispute with Japan into a conflict between China and the U.S., he said.

The zone "is part of a continuous effort to push the USA and Japan back, as both conduct over 500 cases of reconnaissance close to China's borders," said Sun. "China is nervous and uncomfortable about this."

China has also said it owns the South China Sea, and is staking vast territorial claims there while angering neighbors including Vietnam and the Philippines. Further tensions are inevitable as other powers react to China expanding its strategic space, said Shi Yinhong, an international relations expert at People's University in Beijing.

China and the U.S. have made "remarkable progress" in co-operating on international security issues such as Iran and Syria, but the air defense zone offers a reminder of fundamental tensions between the two powers, he said.

"Although Sino-American economic and other relations could be in relatively good shape, the strategic rivalry becomes more profound and prominent," said Shi, also an adviser to China's State Council, or Cabinet.

Wang Chanfeng, 20, a college student, defended China's aggressive actions as he talked about his love for the popular video game "Glorious Mission," in which the player shoots down U.S. B-52s like the ones that recently thundered over the East China Sea air defense zone without notifying China.

"In the past century, China's national defense was weak, this game could wake up the feeling of national mission and the sense of crisis of China's new generation," said Wang, who is majoring in software engineering in northwest China's Ningxia province.

Wang said he is optimistic of improving ties in most respects.

"I don't think just a game could inflame sentiment towards 'enemy' countries," he said. "We are in a new era, most young people are educated, they have their own thoughts, they won't simply hate another country, but we have a sense of crisis."